Appliance & Cloud — a selection guide on when an SBC is truly required to connect Telkom SIP Trunks to Retell AI, VAPI, LiveKit, CloudTalk, Sprinklr, and Freshcaller.

Sangoma SBC—available both as an on-premises Appliance and as a Cloud/VM instance—serves as a bridging point between Telkom SIP Trunks (both on-premises and cloud-based) and various AI Voice Agent platforms. However, the requirement for an SBC varies depending on the target platform: while some platforms accept direct SIP trunk connections and treat TLS as optional, others explicitly mandate or recommend an SBC as part of their official architecture. This document outlines these requirements on a per-platform basis and details the role of Sangoma SBC in each scenario.

Why Telkom Trunks Cannot Be Directly Connected to AI Platforms

Telkom SIP Trunks are fundamentally engineered for traditional inter-PBX communication, whereas modern AI Voice Agent platforms rely on varying standards for signaling, security, and codecs. Without an appropriate bridging layer, three common issues typically arise:

• Encryption — Conventional Telkom trunks generally run over unencrypted UDP, whereas several AI platforms recommend or mandate SIP over TLS along with SRTP media encryption.

• Codec Mismatch — Telkom trunks typically utilize G.711/G.729, while many AI platforms require wideband codecs like Opus or G.722, necessitating real-time transcoding.

• Network Security — Exposing a trunk directly to the public internet without a protective layer leaves the network vulnerable to unauthorized registrations, SIP flooding, and potential toll fraud.

What Is Sangoma SBC?

A Session Border Controller resides between the Telkom SIP Trunk and your internal communications infrastructure—whether an IP-PBX, contact center, or AI Voice Agent platform—performing four primary roles for every call session:

• Interoperability & Transcoding — Bridges differences in codecs, signaling formats, and protocol variants across vendor platforms.

• End-to-End SIP TLS & SRTP Encryption — Encrypts call signaling and media streams across the network path, preventing eavesdropping and tampering.

• Routing, Load Balancing & Failover — Intelligently routes call traffic across multiple trunks or AI platforms simultaneously with automated failover capability.

• Threat Protection & Toll Fraud Prevention — Detects and blocks suspicious registration patterns and trunk exploitation attempts in real time.

Two Deployment Models: Appliance vs. Cloud

Both deployment models deliver the same core functions. The differences lie in physical placement, investment model, and how capacity scales with growing call volume.

Model	Ideal For	Session Capacity	Catatan
Sangoma SBC — SMB Appliance	Small-to-medium offices with on-premises Telkom trunks	5–30 concurrent sessions	Physical on-site hardware with complete control over local data
Sangoma SBC — Medium/Large Appliance	Enterprises with moderate call volumes	25–250 concurrent sessions	Ideal for local data compliance and strict regulatory environments
Sangoma SBC — Hybrid/Carrier Appliance	Large enterprises and service providers / carriers	Up to 4,000 sessions	Combines virtual machine flexibility with hardware-grade scalability
Sangoma SBC — Cloud (Virtual Machine)	Cloud trunks & integrations with cloud-based AI platforms	Up to 1,000 concurrent sessions	Elastic, zero hardware footprint, and managed via WebGUI